Belfast Auxiliary Bishop Donal McKeown said protests are not sectarian in the sense of Catholic versus Protestant, but "clearly, sectarian elements have surfaced again."
"It is precisely because Belfast is no longer a unionist-dominated city that the problem has arisen," he told Catholic News Service in an email interview in early January.
"Belfast City Council has taken a decision, and some loyalists are protesting against it," he said.
Although largely self-governing, Northern Ireland is part of the United Kingdom, and Protestants traditionally align themselves as loyalists.
Nationalists, historically Catholic, have maintained that Northern Ireland should be part of the Irish Republic.
Belfast City Hall has traditionally been seen as a bastion of unionism, or loyalists.
But Councilor Tim Attwood, a spokesman for the Social Democratic and Labor Party, said the Dec. 3 vote to restrict how often the Union Jack is flown at City Hall reflects the changes in demographics of Belfast.
"Belfast is now a city almost evenly divided between nationalists/Catholics and unionist/Protestants, as shown by the most recent census figures," he told CNS. "Belfast is now a hung council. There is no overall majority among the nationalist or unionist parties."
In the small Catholic enclave of Short Strand in predominantly loyalist East Belfast, parishioners at St. Matthew's Church have been affected by more than a month of nightly violence.
"This area has been a flashpoint for many years, not just for the last 40 years but going back 100 years," said Willie Ward, a businessman and lay spokesman for St. Matthew's. It is also "one of the most blighted parts of Belfast, with upwards of 70 percent unemployment."
He said the demonstrators "are holding their protests a short distance away from our church. They have been fighting and rioting with the police, which has resulted in the roads in and around our area being blocked. This small Catholic community cannot freely go in and out of town because we are afraid. It has caused problems for me as a local businessman."
His business' earnings the first week of January were down 75 percent from the same period in 2012.
"People won't go out at night in the area because they are afraid," he said. "We are living just yards away from the riots. They have come down and thrown rocks and missiles at our church."
The church has a nearly constant police presence for protection, especially at Mass times, to deter those intent on stone-throwing and attacking the building.
"We know what it is like to live under fear and under attack," Ward said. "Just a mile up the road you have areas that are affluent and Protestant, and they are not out rioting. The disturbances are taking place in the working-class areas because there is no leadership within the community for the working class youth."
He also said he believed that, as some police have said, loyalist paramilitaries were behind the violence.
"Hopefully we will come through this when the Protestant politicians get their act together and realize that they have to sit down with the nationalist and other councilors to debate this. They can't solve this on their own," he said.
Bishop McKeown noted that at another parish, "an attempt was made to burn the church on Dec. 22, and the boiler house was destroyed."
However, he added, at the Christmas Vigil Mass in the church, the bishop has met Church of Ireland, Methodist and Presbyterian ministers, plus 20 young people from a local church youth group who were there in solidarity with their Catholic neighbors.